gitlab: Add ruby script for continuous extending of bot tokens

We are not on top of expiring bot tokens and we usually only notice when someone else points it out.

It is also a bit cumbersome to add new bot tokens, so avoid the issue altogether, by just extending the lifetime of the bot tokens continuously.

Fix #617 (closed)

approved this merge request

mentioned in commit f513000f

merged manually

mentioned in merge request !909 (merged)